Replacing rear brake pads (Mercedes-Benz Sprinter 903)

The pads should be replaced if the linings are worn to a thickness of less than 2 mm. This can be checked by removing the wheel with the caliper installed, as described in subsection 12.3.1when replacing, please refer to the drawing 279. Model 412D is equipped with two-piston calipers. The brake pads must be replaced in the following sequence:

• unscrew the brake fluid reservoir cap;
• press the brake pedal several times to relieve the vacuum in the system. Place the rear of the vehicle on supports and remove the rear wheels;

• disconnect the brake pad wear sensor wire as shown in the figure 280;
• using a screwdriver and pliers, remove both retaining clips from the brake shoe pins 4 (see figure 279);
• use a screwdriver to pry up the ends of spring 2 and remove it;

• from the back of the caliper, use a screwdriver to pry up both caps of the mounting bolts shown in Fig. 281 and unscrew the bolts with a hex key. After unscrewing the bolts, remove the caliper cylinder. Hang the cylinder on a wire from the front axle so that it does not hang on the brake hose. Remove the shoe from the removed cylinder;
• remove the second pad from the caliper bracket;
• thoroughly clean the caliper receiving splines and check that the mudguards and cylinder are not damaged;

• if the pads are very worn, you will need to push the piston into the brake cylinder as shown in the picture 275. To do this, you can also install the inner shoe on the piston and slowly press it inward. At the same time, make sure that the brake fluid does not leak from the reservoir. If necessary, pump out some liquid.

When installing the pads, the following operations must be performed:

• clean the contact surface under the brake pads in the caliper;
• pump out some brake fluid from the master cylinder reservoir as described above;
• push the piston into the cylinder. For this purpose, the clamp shown in the figure is used 275;

• install the shoe with the spring into the caliper cylinder as shown in the figure 276, and press in the direction of the arrow;

• insert the outer shoe into the mounting locations of the caliper bracket so that it occupies the position shown in the figure 273;

• insert the second pad into the caliper bracket. In this case, position its outer side as shown in the figure 282;

• carefully position the cylinder body over the pads and screw the mounting bolts through the pads into the caliper bracket. Wrap them with a hexagon as shown in the picture 277, torque 25–28 Nm;
• after tightening the bolts, put the caps on them;

• install the spring into the caliper and bracket. Check that the spring is installed correctly (figure 283);
• twist the wear sensor wire into a spiral and connect it to the caliper contact;
• press the brake pedal hard several times to get the pads to fit onto the disc;
• if necessary, add brake fluid to the reservoir;
• install the wheels, lower the vehicle and tighten the wheel bolts to 160–180 N·m;
• after installation, press the brake pedal several times until its normal travel is established. If this is not done, the brakes may not work when the vehicle is first tested while moving. If the pedal "fails", check the tightness of the system. During the first trips after installing new pads, do not brake too sharply. To ensure that the brakes are properly adjusted, brake from 80 km/h to 40 km/h several times while pressing the pedal smoothly. Wait after each braking to ensure that the brakes do not overheat.

Recommendations for the use of brake pads

If the pads are too worn, you should make sure that the pistons of both brake calipers move normally. Otherwise, it is recommended to check the operation of the clamps at a service station. The pads should be replaced when their linings are worn to a thickness of 2.0 mm or less. You should also replace any brake pads that are oily or contaminated with grease. Only genuine Mercedes-Benz brake pads should be used and replaced only as a set. If the pads are worn down to the metal, the brake disc may be damaged. This, of course, must be avoided under all circumstances.

Brake discs containing traces of friction material from the linings should be thoroughly cleaned before installing new pads. New pads need to be broken in. To do this, smoothly press the brake pedal and brake several times from 80 km/h to 40 km/h. After each braking, it is necessary to pause so that the brakes do not overheat. Until the brake pads have been run in, it is important to avoid emergency braking.